1. Field of Invention
The present invention relates to a two-terminal nonlinear device used as a switching device, a method for manufacturing the two-terminal nonlinear device, and a liquid-crystal display panel including the two-terminal nonlinear device.
2. Description of Related Art
An active matrix-type liquid-crystal display may include an active-matrix substrate in which a switching device is provided for each pixel area to form a matrix array. Liquid crystals may be packed between opposing substrates provided with color filters. In such a liquid-crystal display, alignment of the liquid crystal in each pixel area is controlled to display desired image information. In general, a three-terminal device such as a thin film transistor (TFT) or a two-terminal device such as a metal/insulating material/metal (MIM) nonlinear device is used as a switching device. A two-terminal device used as a switching device is more advantageous than a three-terminal device since two-terminal devices are free of cross-over shorting and can be manufactured by a simpler process.
Japanese Unexamined Patent Publication No. 63-50081 discloses a technique for improving nonlinearity of a MIM nonlinear device. In this technique, a tantalum film is subjected to anodic oxidation and heat-treated at 400.degree. C. to 600.degree. C. in a nitrogen atmosphere to improve nonlinearity, especially sharpness of the voltage-current characteristic. However, sufficient nonlinearity has not yet been achieved even by this technique.